反应详情

A mixture of 12.97 g (0.0436 mol) of the ketal of (A) and 200 ml of 10% H2SO4 /tetrahydrofuran (2:1) solution is stirred at 60°-70° C. for 4 hrs and is then allowed to stand at room temperature for 3 days. The mixture is diluted with water and extracted with methylene chloride. The combined extracts are washed with brine, dried over Na2SO4, and concentrated in vacuo. Trituration with ethyl ether gives 10.07 g (91%) of title compound as a white solid: m.p. 183°-185° C.; IR (KBr) 3410, 1710, 1585, and 1160 cm-1 ; NMR (CDCl3) δ 7.79 (d, 2H), 6.98 (d, 2H), 3.79 (t, 4H), 3.04 (s, 3H), and 2.61 (t, 4H).

1. waitto stand at room temperature for 3 days
2. extractionextracted with methylene chloride
3. washThe combined extracts are washed with brine
4. dry with materialdried over Na2SO4
5. concentrationconcentrated in vacuo